CN113625517A - Wavelength conversion device - Google Patents
Wavelength conversion device Download PDFInfo
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- CN113625517A CN113625517A CN202110258994.7A CN202110258994A CN113625517A CN 113625517 A CN113625517 A CN 113625517A CN 202110258994 A CN202110258994 A CN 202110258994A CN 113625517 A CN113625517 A CN 113625517A
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/2006—Lamp housings characterised by the light source
- G03B21/2033—LED or laser light sources
- G03B21/204—LED or laser light sources using secondary light emission, e.g. luminescence or fluorescence
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/16—Cooling; Preventing overheating
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/2066—Reflectors in illumination beam
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/208—Homogenising, shaping of the illumination light
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Abstract
A wavelength conversion device includes a substrate, a photoluminescent layer, a spot-adjusting layer, and a reflective layer. The photoluminescent layer is disposed over the substrate and configured to receive incident light and convert the incident light into excitation light. The light spot adjusting layer is arranged between the substrate and the photoluminescent layer and configured to receive the excitation light and the unconverted incident light so as to adjust light paths of the excitation light and the unconverted incident light, wherein the refractive index of the photoluminescent layer is different from that of the light spot adjusting layer. The reflection layer is arranged between the facula adjusting layer and the substrate and is configured to reflect incident light and exciting light.
Description
Technical Field
The present disclosure relates to a wavelength conversion device.
Background
In recent years, optical projectors have been widely used in many fields and various places, such as schools, homes, and businesses.
In one type of projector, a laser source provides a first light incident on a fluorescent material, and then emits a second light. In this regard, a fluorescent material and a reflective material are coated on a fluorescent wheel, and the fluorescent wheel is driven by a motor to rotate at a high speed, and finally light reflected by the fluorescent wheel forms an image. With the increasing demand for brightness of optical projectors, how to make fluorescent materials and reflective materials exert better effects is an important issue at present.
Disclosure of Invention
According to some embodiments of the present disclosure, a wavelength conversion device includes a substrate, a photoluminescent layer, a speckle adjustment layer, and a reflective layer. The photoluminescent layer is disposed over the substrate and configured to receive incident light and convert the incident light into excitation light. The light spot adjusting layer is arranged between the substrate and the photoluminescent layer and configured to receive the excitation light and the unconverted incident light so as to adjust light paths of the excitation light and the unconverted incident light, wherein the refractive index of the photoluminescent layer is different from that of the light spot adjusting layer. The reflection layer is arranged between the facula adjusting layer and the substrate and is configured to reflect incident light and exciting light.
In some embodiments of the present disclosure, the thermal conductivity of the speckle-adjusting layer is between 0.1W/mK and 40W/mK.
In some embodiments of the present disclosure, the speckle adjusting layer includes a matrix and a plurality of light diffusion particles, and a refractive index of the matrix is different from a refractive index of the light diffusion particles.
In some embodiments of the present disclosure, the matrix may include a single crystal structure, a polycrystalline structure, a continuous structure, or a combination thereof.
In some embodiments of the present disclosure, the substrate may include silica gel, glass, diamond, sapphire, yttria, sintered metal oxide, or combinations thereof.
In some embodiments of the present disclosure, the light diffusing particles may include alumina, titania, yttria, silica, single crystal quartz, sintered metal oxides, or combinations thereof.
In some embodiments of the present disclosure, the concentration of the light diffusing particles is between 10 wt% and 70 wt% based on the total weight of the speckle adjusting layer.
In some embodiments of the present disclosure, the light diffusing particles have a particle size of 10nm to 10 μm.
In some embodiments of the present disclosure, the thermal conductivity of the light diffusing particles is greater than the thermal conductivity of the matrix.
In some embodiments of the present disclosure, the speckle adjusting layer further includes a plurality of first photoluminescent particles, and a refractive index of the first photoluminescent particles is greater than a refractive index of the matrix.
In some embodiments of the present disclosure, the photoluminescent layer includes a plurality of second photoluminescent particles, and a wavelength conversion efficiency of the first photoluminescent particles in the flare adjusting layer is lower than a wavelength conversion efficiency of the second photoluminescent particles in the photoluminescent layer.
In some embodiments of the present disclosure, the wavelength conversion efficiency of the flare adjusting layer is less than 80% of the wavelength conversion efficiency of the photoluminescent layer.
In some embodiments of the present disclosure, the photoluminescent layer includes a plurality of second photoluminescent particles, and a particle size of the first photoluminescent particles is smaller than a particle size of the second photoluminescent particles.
In some embodiments of the present disclosure, the first photoluminescent particles have a particle size of 1 μm to 20 μm, and the second photoluminescent particles have a particle size of 20 μm to 35 μm.
In some embodiments of the present disclosure, the concentration of the first photoluminescent particles is between 40 wt% and 80 wt%, and the concentration of the second photoluminescent particles is between 70 wt% and 90 wt%.
In some embodiments of the present disclosure, a ratio of the concentration of the light diffusing particles to the concentration of the first uniform light emitting particles is between 0.5 and 1.2.
In some embodiments of the present disclosure, the thickness of the speckle adjustment layer is between 10 μm and 500 μm, and the thickness of the photoluminescent layer is between 25 μm and 300 μm.
According to the above embodiments of the present disclosure, since the flare adjusting layer can prevent the flare generated by the excitation light and the incident light from being excessively concentrated in the photo-luminescent layer, the flare can be uniformly distributed in the photo-luminescent layer. Therefore, the wavelength conversion device can exert better optical conversion efficiency, and provide higher brightness and larger light-emitting area. In addition, the thickness of the photoluminescent layer can be reduced, which is beneficial to the heat dissipation of the photoluminescent layer and the brightness improvement of the wavelength conversion device. In addition, the high energy thermal energy generated by the concentrated spots in the photoluminescent layer may be reduced and the lifetime of the wavelength conversion device may be correspondingly extended.
Drawings
The foregoing and other objects, features, advantages and embodiments of the disclosure will be apparent from the following more particular description of the embodiments, as illustrated in the accompanying drawings in which:
fig. 1 illustrates a perspective view of a wavelength conversion device according to some embodiments of the present disclosure;
FIG. 2 illustrates a cross-sectional view of the wavelength conversion device of FIG. 1 along line a-a', according to some embodiments of the present disclosure;
FIG. 3 is a schematic cross-sectional view of the wavelength conversion device of FIG. 1 along the line a-a' according to other embodiments of the present disclosure;
FIG. 4 is a schematic cross-sectional view of the wavelength conversion device of FIG. 1 along the line a-a' according to other embodiments of the present disclosure;
FIG. 5 is a schematic cross-sectional view of the wavelength conversion device of FIG. 1 along the line a-a' according to other embodiments of the present disclosure;
fig. 6 shows a schematic diagram of wavelength conversion efficiency versus applied current of the wavelength conversion devices of comparative example 1 and example 1;
fig. 7 shows a schematic diagram of wavelength conversion efficiency versus applied current of the wavelength conversion devices of comparative example 1 and example 2; and
fig. 8 is a schematic diagram showing the wavelength conversion efficiency versus applied current of the wavelength conversion devices of comparative example 1 and example 3.
[ notation ] to show
100,100a,100b,100c wavelength conversion device
110,110a,110b,110c substrate
111: surface
120,120a,120b,120c reflective layer
121 surface of
130,130b,130c spot adjusting layer
131 the first surface
132 second surface
132a,132b,132c substrate
134a,134c light diffusing particles
136b,136c photoluminescent particles
140,140a,140b,140c photoluminescent layer
142,142a,142b,142c photoluminescent particles
T1, T2 thickness
a-a' line segment
Detailed Description
In the following description, numerous implementation details are set forth in order to provide a thorough understanding of the present disclosure. It should be understood, however, that these implementation details are not to be interpreted as limiting the disclosure. That is, in some embodiments of the disclosure, these implementation details are not necessary, and thus should not be used to limit the disclosure. In addition, some conventional structures and elements are shown in simplified schematic form in the drawings. In addition, the dimensions of the various elements in the drawings are not necessarily to scale, for the convenience of the reader.
Further, as used herein, reference to "about," "approximately," or "substantially" generally means that the numerical error or range is within twenty percent, preferably within ten percent, and more preferably within five percent. Unless expressly stated otherwise, all numerical values mentioned are to be regarded as approximations, i.e., as having the error or range indicated as "about", "approximately" or "substantially".
To prevent light spots in the photoluminescent layer of a wavelength conversion deviceOver-concentration (i.e., too high of a spot concentration), the present disclosure provides a wavelength conversion device that includes a spot-adjusting layer. It should be noted that when the light beam irradiates the object, a "light spot" is generated on the surface of the object, and the "light spot concentration" herein refers to the power of the light spot per unit area, and may be expressed by the unit "W/cm2"means. In other words, when the energy transfer rate of the light beam is fixed, the larger the area of the light spot is, the lower the power of the light spot per unit area is, that is, the lower the density (concentration ratio) of the light spot is. By adjusting the characteristics of the spot adjusting layer and the particles in the spot adjusting layer, it is possible to favorably prevent the spots from being excessively concentrated in the wavelength conversion device. Based on the above, the light spots can be uniformly distributed in the photoluminescent layer, representing that photoluminescent particles (e.g., phosphor) in the photoluminescent layer can be effectively utilized, so the wavelength conversion device can exert better optical conversion efficiency and provide higher brightness and larger light emitting area. In addition, the thickness of the photoluminescent layer can be reduced, which is beneficial to the heat dissipation of the photoluminescent layer and the brightness improvement of the wavelength conversion device. In addition, the high energy thermal energy generated by the concentrated spots in the photoluminescent layer may be reduced and the lifetime of the wavelength conversion device may be correspondingly extended.
Fig. 1 illustrates a perspective view of a wavelength conversion device 100 according to some embodiments of the present disclosure. Fig. 2 illustrates a cross-sectional view of the wavelength conversion device 100 of fig. 1 along the line a-a', according to some embodiments of the present disclosure. Please refer to fig. 1 and fig. 2. The wavelength conversion device 100 includes a substrate 110, a reflective layer 120, a speckle adjusting layer 130, and a photoluminescent layer 140. The spot-adjusting layer 130 has a first surface 131 and a second surface 132 opposite to the first surface 131. The substrate 110 is located on the first surface 131 of the speckle adjusting layer 130, and the photoluminescent layer 140 is located on the second surface 132 of the speckle adjusting layer 130. In other words, the substrate 110 and the photoluminescent layer 140 are located on opposite sides of the speckle adjustment layer. In addition, the reflective layer 120 is disposed between the speckle adjusting layer 130 and the substrate 110. In some embodiments, the wavelength conversion device 100 is a reflective fluorescent color wheel that generates excitation light by absorbing a light beam (e.g., laser light). In detail, the light beam is absorbed by the photoluminescent layer 140 to generate an excitation light, and a portion of the excitation light further enters and diffuses in the speckle adjustment layer 130, and is then reflected by the reflective layer 120 and emitted out of the wavelength conversion device 100 for imaging. In some embodiments, the wavelength conversion device 100 is connected to a motor through a drive shaft such that when the motor drives the drive shaft to rotate, the wavelength conversion device 100 may rotate therewith.
In some embodiments, the substrate 110 may be, for example, a sapphire substrate, a glass substrate, a borosilicate glass substrate, a floating borosilicate glass substrate, a fused silica substrate, or a calcium fluoride substrate, a ceramic substrate, an aluminum substrate, or a combination thereof. However, the material of the substrate 100 is not limited thereto, and the material of the substrate 110 may be adjusted according to actual needs.
In some embodiments, the reflective layer 120 may be made of a material including metal (e.g., silver and/or aluminum), such that a surface of the reflective layer 120 facing away from the substrate 110 may have a metal reflective surface 121 to enhance reflection of the light beam irradiated toward the substrate 110 and further provide better optical conversion efficiency for the wavelength conversion device 100. In other embodiments, the reflective layer 120 may include scattering particles, such as titanium oxide and/or zirconium oxide. In some other embodiments, the reflective layer 120 may be a metal oxide plate comprising materials such as aluminum oxide and/or beryllium oxide. In an alternative embodiment, the reflective layer 120 may include a multilayer dielectric film made of materials such as silicon oxide and aluminum oxide.
In some embodiments, the spot adjusting layer 130 can adjust the concentration of the light spot in the photoluminescent layer 140. In some embodiments, spot-adjusting layer 130 can adjust the concentration of the light spot produced by the excitation light in photoluminescent layer 140. In detail, when the excitation light is converted from the incident light and penetrates through the interface between the photoluminescent layer 140 and the spot adjusting layer 130, the excitation light may diffuse to the spot adjusting layer 130 and/or be reflected by the spot adjusting layer 130 due to the difference in refractive index between the photoluminescent layer 140 and the spot adjusting layer 130. Then, the excitation light diffused into the speckle adjusting layer 130 is further reflected back into the speckle adjusting layer 130 and the photoluminescent layer 140 by the reflective layer 120. Based on the above, the excitation light is transmitted through the wavelength conversion device 100 through various optical paths, so that the optical path of the excitation light transmitted through the wavelength conversion device 100 is lengthened. As such, the excitation light can be diffused toward the photo-luminescent layer 140 with a low distribution density to reduce the concentration of the light spot in the photo-luminescent layer 140. In some embodiments, the refractive index of the photoluminescent layer 140 is different from the refractive index of the speckle-adjusting layer 130, so that the optical path can be well adjusted at the interface between the photoluminescent layer 140 and the speckle-adjusting layer 130. In a preferred embodiment, the refractive index of the speckle adjustment layer 130 is greater than the refractive index of the photoluminescent layer 140.
In some other embodiments, the spot adjusting layer 130 may adjust the concentration of a spot generated by incident light in the photoluminescent layer 140 that is not converted to excitation light. In detail, when the incident light penetrates through the photoluminescent layer 140 to reach the interface between the photoluminescent layer 140 and the spot adjusting layer 130, the excitation light may diffuse to the spot adjusting layer 130 and/or be reflected by the spot adjusting layer 130 due to the difference in refractive index between the photoluminescent layer 140 and the spot adjusting layer 130. Then, the incident light diffused into the speckle adjusting layer 130 is further reflected back into the speckle adjusting layer 130 and the photoluminescent layer 140 by the reflective layer 120. Based on the above, the incident light is transmitted through the wavelength conversion device 100 through a plurality of optical paths, so that the optical path of the incident light transmitted through the wavelength conversion device 100 is lengthened. As a result, the incident light can be diffused toward the photoluminescent layer 140 with a low distribution density, so as to reduce the concentration of the light spot in the photoluminescent layer 140.
Since the spot adjusting layer 130 can prevent spots generated by the excitation light and the incident light from being excessively concentrated in the photoluminescent layer 140, the spots can be uniformly distributed in the photoluminescent layer 140. Based on the above, the photoluminescent particles 142 (e.g., cerium phosphor) in the photoluminescent layer 140 can be effectively utilized, so the wavelength conversion device 100 can exert better optical conversion efficiency and provide higher brightness and larger light emitting area. In addition, since the photoluminescent particles 142 in the photoluminescent layer 140 can be effectively utilized, the thickness T1 of the photoluminescent layer 140 can be reduced, which is beneficial to heat dissipation of the photoluminescent layer 140 and brightness improvement of the wavelength conversion device. For example, the thickness T1 of the photoluminescent layer 140 may be between 25 μm and 300 μm. In addition, the high energy thermal energy generated by the concentrated light spot in the photoluminescent layer 140 can be reduced, and the lifetime of the wavelength conversion device 100 can be correspondingly extended.
In some embodiments, the thickness T2 of the speckle adjustment layer 130 may be between 10 μm and 500 μm, so that light (including excitation light and incident light) may be well guided and uniformly transferred into the photoluminescent layer 140, and so that the total thickness of the wavelength conversion device 100 may be kept within a suitable range. In detail, if the thickness T2 of the light spot adjusting layer 130 is less than 10 μm, the light spots in the photoluminescent layer 140 may be too concentrated, which may further adversely affect the optical conversion efficiency, brightness and heat dissipation; if the thickness T2 of the speckle adjustment layer 130 is greater than 500 μm, the total thickness of the wavelength conversion device 100 may be too large, not only affecting the appearance of the wavelength conversion device 100, but also causing material waste.
In some embodiments, the speckle adjustment layer 130 may be made of a material including a single crystal structure, a polycrystalline structure, a continuous structure, or a combination thereof. Light (including excitation light and incident light) can be well diffused to the photoluminescent layer 140 through the above materials, so that the reflected incident light has more chance to encounter the phosphor in the photoluminescent layer 140 and be converted into excitation light, and the spots in the photoluminescent layer 140 can be prevented from being excessively concentrated. In some embodiments, the speckle adjustment layer 130 may be made of a material including silica gel, glass, diamond, sapphire, yttria, sintered metal oxide, or a combination thereof. The material may be transparent, substantially transparent (i.e., greater than 90% visible light transmission), or translucent (i.e., between 30% and 90% visible light transmission). The above materials may provide a thermal conductivity of the spot-adjusting layer 130 of between 0.1W/m-K and 40W/m-K. If the thermal conductivity of the light spot adjusting layer 130 is less than 0.1W/m · K, the light spot adjusting layer 130 cannot effectively conduct heat energy, and the photoluminescent layer 140 is easily thermally quenched. In addition, the thermal conductivity of the spot adjusting layer 130 may be greater than 10W/m · K to achieve a better heat dissipation effect.
In some embodiments, the photoluminescent particles 142 in the photoluminescent layer 140 can include garnet-structured silicate phosphors, nitride phosphors, Y3Al5O12(YAG)、Tb3Al5O12(TAG) or Lu3Al5O12(LuAG) phosphor or a combination thereof, but not intended to limit the present disclosure.
Fig. 3 is a schematic cross-sectional view of the wavelength conversion device 100 of fig. 1 along the line a-a' (which will be referred to as the wavelength conversion device 100a hereinafter) according to other embodiments of the present disclosure. Referring to fig. 3, at least one difference between the wavelength conversion device 100a of fig. 3 and the wavelength conversion device 100 of fig. 2 is: the speckle adjustment layer 130a of the wavelength conversion device 100a includes a matrix 132a and a plurality of light diffusion particles 134a distributed in the matrix 132 a. The light diffusion particles 134a are configured to adjust the degree of light diffusion. In detail, the light diffusion particles 134a may adjust the light path, thereby preventing the light emitted toward the photoluminescent layer 140a from being excessively dispersed. Therefore, the light emitted toward the photoluminescent layer 140a can be appropriately condensed, facilitating the collection of the light. In the present embodiment, not only the problem of excessive concentration of light spots can be avoided, but also light from the wavelength conversion device 100a can be easily collected.
In some embodiments, the material of the matrix 132a may refer to the material of the speckle adjustment layer 130 of the wavelength conversion device 100 described above. In some embodiments, the material of the light diffusion particles 134a may include alumina, titania, yttria, silica, single crystal quartz, sintered metal oxides, or combinations thereof. In some embodiments, the refractive index of the matrix 132a is different from that of the light diffusion particles 134a, so that the optical path at the interface of the matrix 132a and the light diffusion particles 134a can be well adjusted. In a preferred embodiment, the refractive index of the light diffusing particles 134a is greater than the refractive index of the matrix 132 a. In some embodiments, the concentration of the light diffusion particles 134a is between 10 wt% and 70 wt% when calculated on the total weight of the spot adjusting layer 130, thereby preferably adjusting the light path in the spot adjusting layer 130 a. In detail, if the concentration of the light diffusion particles 134a is less than 10 wt%, the light path may not be well adjusted, and the light emitted toward the photoluminescent layer 140a may be excessively dispersed, resulting in difficulty in collecting the light; if the concentration of the light diffusion particles 134a is higher than 70 wt%, the light diffusion effect may not be well achieved, and the above-described advantages (e.g., prevention of excessive concentration of light spots and avoidance of excessive dispersion of light) may not be well achieved.
In some embodiments, the particle size (D50) of the light diffusion particles 134a is between 10nm and 10 μm to better adjust the light path in the speckle adjustment layer 130 a. It should be understood that the term "particle size (D50)" refers to the particle size of the light diffusion particles 134a when the percentage of the particle size distribution reaches 50%, i.e. half of the light diffusion particles 134a have a larger particle size than the particle size (D50), and half of the light diffusion particles 134a have a smaller particle size than the particle size (D50). In detail, if the particle diameter (D50) of the light diffusion particles 134a is less than 10nm, the light in the speckle adjustment layer 130a may not easily encounter the light diffusion particles 134a, causing the light path to be not well adjusted, resulting in difficulty in collecting the light; if the particle diameter (D50) of the light diffusion particles 134a is greater than 10 μm, the light diffusion particles 134a may seriously affect the penetration of light in the flare adjusting layer 130a, resulting in excessively complicated diffusion of light and failing to achieve the above-described advantages (e.g., preventing excessive concentration of light spots and avoiding excessive divergence of light). In some embodiments, the thermal conductivity of the host 132a may be referred to the thermal conductivity of the foregoing speckle adjustment layer 130, so that the speckle adjustment layer 130a may have good thermal conductivity to effectively conduct thermal energy that may cause thermal quenching of the phosphor in the photoluminescent layer 140a and extend the service life of the wavelength conversion device 100 a. In some embodiments, the thermal conductivity of the light diffusing particles 134a may be greater than 1.5W/m-K to provide good thermal conductivity to the spot adjusting layer 130 a. In some embodiments, the thermal conductivity of the light diffusing particles 134a may be greater than the thermal conductivity of the matrix 132 a.
FIG. 4 is a schematic cross-sectional view of the wavelength conversion device 100 of FIG. 1 along the line a-a' (which will be referred to as the wavelength conversion device 100b hereinafter) according to other embodiments of the present disclosure. Referring to fig. 4, at least one difference between the wavelength conversion device 100b of fig. 4 and the wavelength conversion device 100 of fig. 2 is: the speckle adjustment layer 130b of the wavelength conversion device 100b includes a matrix 132b and a plurality of photoluminescent particles 136b distributed in the matrix 132 b. For simplicity and clarity, the photoluminescent particles 136b in the speckle-adjusting layer 130b are referred to as first photoluminescent particles 136b, and the photoluminescent particles 142b in the photoluminescent layer 140b are referred to as second photoluminescent particles 142 b. The first photoluminescent particles 136b are configured to further convert incident light delivered to the speckle adjustment layer 130b into excitation light. Thereby, the brightness of the wavelength conversion device 100b can be further improved. In addition, the first photoluminescent particles 136b are also configured to adjust the degree of light diffusion, which performs the same function as the aforementioned light diffusion particles 134 a. As such, the light emitted toward the photoluminescent layer 140b can be properly condensed, facilitating the collection of the light. In this embodiment, the brightness of the wavelength conversion device 100b can be further improved compared to the wavelength conversion device 100a shown in fig. 3.
In some embodiments, the refractive index of the first photoluminescent particles 136b is greater than the refractive index of the matrix 132b, so that incident light passing from the photoluminescent layer 140b to the speckle-adjusting layer 130b has a higher chance of being reflected back into the photoluminescent layer 140 b. Based on the above, the light converted into the excitation light in the flare adjusting layer 130b can be efficiently reflected toward the outside of the wavelength conversion device 100 b.
In some embodiments, the concentration of the first photoluminescent particles 136b in the flare adjusting layer 130b is lower than the concentration of the second photoluminescent particles 142b in the photoluminescent layer 140b, and the particle size of the first photoluminescent particles 136b in the flare adjusting layer 130b is smaller than the particle size of the second photoluminescent particles 142b in the photoluminescent layer 140 b. Specifically, the concentration of the first photoluminescent particles 136b in the flare adjusting layer 130b is between 40 wt% and 80 wt%, and the concentration of the second photoluminescent particles 142b in the photoluminescent layer 140b is between 70 wt% and 90 wt%. In addition, the first photoluminescent particles 136b have a particle size between 1 μm and 20 μm, and the second photoluminescent particles 142b have a particle size between 20 μm and 35 μm. Based on the above, the wavelength conversion efficiency (i.e., the luminous flux per unit volume) of the first photoluminescent particles 136b in the flare adjusting layer 130b is lower than that of the second photoluminescent particles 142b in the photoluminescent layer 140 b. In addition, the wavelength conversion efficiency of the spot adjusting layer 130b is lower than 80% of the wavelength conversion efficiency of the photo-luminescent layer 140 b. In this way, most of the light can be converted into excitation light by the photo-luminescent layer 140b, and the spot adjusting layer 130b can mainly adjust the concentration of the light spot. More specifically, since the concentration of the first photoluminescent particles 136b in the flare adjusting layer 130b is relatively low and the particle size of the first photoluminescent particles 136b is relatively small, the light transmitted into the flare adjusting layer 130b is relatively difficult to encounter the first photoluminescent particles 136b, and thus the light has more chances to be simply scattered only by the matrix 132b in the flare adjusting layer 130b, so that the advantages of the wavelength conversion device 100 as shown in fig. 2 can be well achieved. In some embodiments, the wavelength of the first photoluminescent particles 136b can be designed to be different from the wavelength of the second photoluminescent particles 142b according to the actual requirement of the wavelength conversion device 100 b.
FIG. 5 is a schematic cross-sectional view of the wavelength conversion device 100 of FIG. 1 along the line a-a' (which will be referred to as the wavelength conversion device 100c hereinafter) according to other embodiments of the present disclosure. Referring to fig. 5, at least one difference between the wavelength conversion device 100c of fig. 5 and the wavelength conversion device 100b of fig. 4 is that: the flare adjusting layer 130c of the wavelength conversion device 100c further includes a plurality of light diffusing particles 134 c. In other words, the flare adjusting layer 130c of the wavelength conversion device 100c includes the light diffusion particles 134c and the first photoluminescent particles 136 c. In some embodiments, the concentration of the light diffusion particles 134c and the concentration of the first photoluminescent particles 136c are both lower than the concentration of the second photoluminescent particles 142c in the photoluminescent layer 140c, thereby providing the advantages described above (e.g., the advantages mentioned in the description of the wavelength conversion device 100 b). For example, the concentration of the light diffusion particles 134c and the concentration of the first photoluminescent particles 136c are between 20 wt% and 30 wt%, respectively, based on the total weight of the speckle adjusting layer 130c, and the concentration of the second photoluminescent particles 142c is between 70 wt% and 90 wt%, based on the total weight of the photoluminescent layer 140 c. In some embodiments, the ratio of the concentration of the light diffusing particles 134c to the concentration of the first photoluminescent particles 136c is between 0.5 and 1.2. As such, the light emitted toward the photoluminescent layer 140c can be properly condensed, facilitating the collection of the light.
In some embodiments, the particle size of the light diffusion particles 134c and the particle size of the first photoluminescent particles 136c in the speckle adjustment layer 130c are both smaller than the particle size of the second photoluminescent particles 142c in the photoluminescent layer 140c, so as to achieve the aforementioned advantages (e.g., the advantages mentioned in the description of the wavelength conversion device 100b) well. In the present embodiment, the light diffusion particles 134c may include a material having high thermal conductivity, such as titanium dioxide (TiO)2). Since the material of the light diffusion particles 134c has high thermal conductivity, thermal energy that may cause thermal quenching of the phosphor may be further efficiently conducted from the photoluminescent layer 140c to the substrate 110 c. In some embodiments, the thermal conductivity of the light diffusing particles 134c may be between 0.1W/m-K and 40W/m-K to better conduct the thermal energy that causes the phosphor thermal quenching and further prevent thermal decay of the photoluminescent layer 140 c.
In the following description, features of the present disclosure will be described in more detail with reference to wavelength conversion devices of some comparative examples and some embodiments of the present disclosure. It is to be understood that the materials used, the masses and proportions, the processing details and the processing procedures may be varied as appropriate without departing from the scope of the present disclosure. Accordingly, the present disclosure should not be construed restrictively by the wavelength conversion device of the embodiments described below. The wavelength conversion devices and their output light intensities of comparative examples and examples are shown in the following table, wherein the comparative example refers to the wavelength conversion device without the speckle adjustment layer, and examples 1, 2 and 3 are the wavelength conversion devices 100,100a and 100b, respectively.
Watch 1
As shown in table one, the output light intensities of examples 1, 2 and 3 are all higher than that of comparative example 1, which shows that the light spots can be uniformly distributed in the photoluminescent layer through the configuration of the light spot adjusting layer of the present disclosure, which means that almost every photoluminescent particle in the photoluminescent layer can be effectively utilized, so that the wavelength conversion device can exert better light conversion efficiency and provide higher brightness (i.e., higher output light intensity). Further, although the light intensity of embodiment 2 is slightly lower than that of embodiment 1, the light diffusion particle of embodiment 2 can adjust the degree of light diffusion, as described above, thereby achieving good light collection. In addition, since the flare adjusting layer of embodiment 3 further includes photoluminescent particles configured to convert incident light into excitation light, in the embodiment shown in table one, embodiment 3 is shown to have the highest light intensity.
Fig. 6 shows a schematic diagram of the wavelength conversion efficiency versus the applied current of the wavelength conversion devices of comparative example 1 and example 1. Fig. 7 is a schematic diagram showing the wavelength conversion efficiency versus applied current of the wavelength conversion devices of comparative example 1 and example 2. Fig. 8 is a schematic diagram showing the wavelength conversion efficiency versus applied current of the wavelength conversion devices of comparative example 1 and example 3. Please refer to fig. 6 to 8. When the applied current is 20% to 60% of the total applied current, the wavelength conversion efficiency of examples 1 to 3 is higher than that of comparative example 1, which shows that the flare adjusting layer of the present disclosure can prevent the flare from being excessively concentrated, so that the flare can be uniformly distributed in the photoluminescent layer, and thus the wavelength conversion device can exert better light conversion efficiency.
According to the above embodiments of the present disclosure, since the flare adjusting layer can prevent the flare from being excessively concentrated, the flare can be uniformly distributed in the photoluminescent layer, i.e. the photoluminescent particles in the photoluminescent layer can be effectively utilized, so that the wavelength conversion device can exert better optical conversion efficiency and provide higher brightness and larger light emitting area. In addition, almost all the photoluminescent particles in the photoluminescent layer can be effectively utilized, so that the thickness of the photoluminescent layer can be reduced, which is beneficial to the heat dissipation of the photoluminescent layer and the improvement of the brightness of the wavelength conversion device. In addition, the high energy thermal energy generated by the concentrated spots in the photoluminescent layer may be reduced and the lifetime of the wavelength conversion device may be correspondingly extended.
Although the present disclosure has been described with reference to particular embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure, and therefore the scope of the present disclosure should be limited only by the terms of the appended claims.
Claims (17)
1. A wavelength conversion device, comprising:
a substrate;
a photoluminescent layer disposed above the substrate and configured to receive an incident light and convert the incident light into an excitation light;
a light spot adjusting layer disposed between the substrate and the photoluminescent layer and configured to receive the excitation light and the unconverted incident light to adjust a light path of the excitation light and the unconverted incident light, wherein a refractive index of the photoluminescent layer is different from a refractive index of the light spot adjusting layer; and
a reflection layer disposed between the spot adjusting layer and the substrate and configured to reflect the incident light and the excitation light.
2. The wavelength conversion device according to claim 1, wherein the spot adjusting layer has a thermal conductivity of 0.1W/m-K to 40W/m-K.
3. The wavelength conversion device according to claim 1, wherein the spot adjusting layer comprises a matrix and a plurality of light diffusing particles, and a refractive index of the matrix is different from a refractive index of the plurality of light diffusing particles.
4. The wavelength conversion device according to claim 3, wherein the matrix comprises a single crystal structure, a polycrystalline structure, a continuous structure, or a combination thereof.
5. The wavelength conversion device according to claim 3, wherein the substrate comprises silica gel, glass, diamond, sapphire, yttria, sintered metal oxide, or a combination thereof.
6. The wavelength conversion device according to claim 3, wherein the light diffusing particles comprise alumina, titania, yttria, silica, single crystal quartz, sintered metal oxides, or combinations thereof.
7. The wavelength conversion device according to claim 3, wherein a concentration of the light diffusing particles is between 10 wt% and 70 wt% based on the total weight of the speckle adjustment layer.
8. The wavelength conversion device according to claim 3, wherein a particle size of the light diffusion particles is between 10nm and 10 μm.
9. The wavelength conversion device according to claim 3, wherein a thermal conductivity of the light diffusing particles is greater than a thermal conductivity of the matrix.
10. The wavelength conversion device according to claim 3, wherein the speckle adjustment layer further comprises a plurality of first photoluminescent particles, and a refractive index of the plurality of first photoluminescent particles is greater than a refractive index of the matrix.
11. The wavelength conversion device according to claim 10, wherein the photoluminescent layer comprises a plurality of second photoluminescent particles, and a wavelength conversion efficiency of the first photoluminescent particles in the flare adjusting layer is lower than a wavelength conversion efficiency of the second photoluminescent particles in the photoluminescent layer.
12. The wavelength conversion device according to claim 11, wherein a wavelength conversion efficiency of the flare adjusting layer is less than 80% of a wavelength conversion efficiency of the photoluminescent layer.
13. The wavelength conversion device according to claim 10, wherein the photoluminescent layer comprises a plurality of second photoluminescent particles, and a particle size of the first photoluminescent particles is smaller than a particle size of the second photoluminescent particles.
14. The wavelength conversion device according to claim 13, wherein the particle size of the first photoluminescent particles is between 1 μm and 20 μm, and the particle size of the second photoluminescent particles is between 20 μm and 35 μm.
15. The wavelength conversion device according to claim 13, wherein a concentration of the first photoluminescent particles is between 40 wt% and 80 wt% and a concentration of the second photoluminescent particles is between 70 wt% and 90 wt%.
16. The wavelength conversion device according to claim 10, wherein a ratio of a concentration of the light-diffusing particles to a concentration of the first uniform light-emitting particles is between 0.5 and 1.2.
17. The wavelength conversion device according to claim 1, wherein a thickness of the flare adjusting layer is between 10 μm and 500 μm, and a thickness of the photoluminescent layer is between 25 μm and 300 μm.
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| US17/144,166 | 2021-01-08 | ||
| US17/144,166 US11287730B2 (en) | 2020-05-07 | 2021-01-08 | Wavelength converting device |
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| CN113625517B (en) | 2022-10-14 |
| TW202142896A (en) | 2021-11-16 |
| TWI767602B (en) | 2022-06-11 |
| US20210349380A1 (en) | 2021-11-11 |
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